In recent ten years, there are many designs and analyses related to light pipes and light guides in the published literatures. Hawthorn examined the transmittance of skew rays in the infrared region, through metal light pipes with ray tracing [1-36]. Gupta et al.
developed a concept of principle section to design the most efficient light pipe geometries [1-35]. Chien and Shieh designed an integrated polarized light guide [1-34]. Siitonen et al. did the LED coupling in to light guides [1-28] [1-33]
. Derlofske et al.
developed a flux confinement diagram (FCD) model to discuss the flux propagation of square light pipes and angular distribution [1-32]. Yang et al. also proposed a polarized light guide [1-31]. Chu and Chern demonstrated no-loss light pipes [1-30]. For reference, we made a list of the relevant literature of light pipes and light guides, which is shown in table 1-5-1 [1-18] ~ [1-36]
.
Table 1-5-1 List of publications regarding light pipe and light guide
Year Authors / Source Characteristics Light pipe Light guide
2008 P. Huang et. al., OL [1-18] Design Y
2001 A. Gupta et. al., AO [1-35] Analysis Y
1999 D. G. Hawthorn and T. Timusk, AO [1-36] Transmittance Y
In Table 1-5-1 we can find that most research works was published in previous five year and this shows that the studies of light pipes and light guides are current trend.
Light pipes and light guides are devices that can guide rays to a specific place.
Generally, light pipe is a self-contained optical device that traps and guides light with no consideration of information propagation from the input to the output aperture, while the light guide could carry information content. Therefore, devices with abilities to carry and propagate light can be referred to a generalized light pipe or light guide, such as different shape of light tubes, the optical fibers, a plastic slab in back light system, and the wedge plate in an ultra-thin display, which is one of the concern of study.
In this dissertation, we would like to put emphasis on the discussions of the transmissive property of different shape of light pipes, the polarization behavior when ray propagates in light pipe, and the image behavior of light guide applied on an ultra-thin display. The dissertation is organized as the following. In chapter 2, we list and summarize the basic terms for light pipes and light guides. In chapter 3, we investigate the irradiance formation of different shapes of straight light pipes. We try to give a quantitative discussion of the uniformity on different light pipe geometries.
In chapter 4, we propose new light pipe application on polarization-preserving angular shifter. We show these two new light pipes can preserve the polarization and deflect the output ray angle as we desired. In chapter 5, we discuss the aberration characteristics of a wedge-plate display optical system and provide two methods to reduce dark zone. We also propose a new type of circular display base on the wedge-plat display. Finally are the conclusions and future works.
References
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"White LED light coupling into light guides with diffraction gratings," Appl.
Opt. 45, 2623-2630 (2006).
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[1-30] S. -C. Chu and J. -L. Chern, "No-loss bent light pipe with an equiangular spiral," Opt. Lett. 30, 3006-3008 (2005).
[1-31] X. Yang, Y. Yan, and G. Jin, "Polarized light-guide plate for liquid crystal display," Opt. Express 13, 8349-8356 (2005).
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1830-1834 (2004)
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